1. Field of the Invention
The present invention relates to an optical recording/reproducing apparatus, and in particular to a head of an optical recording/reproducing apparatus.
2. Description of the Prior Art
As a recording medium for storing a large amount of data, a magnetic disc such as a HDD using a magnetic method, an optical disc such as a CD or DVD using an optical method and a photomagnetic disc, etc. using a photomagnetic effect are used.
The optical disc using the optical method should have a small bit (recording mark) size and a narrow track width in order to have a high-density recording capacity. However, because a spot size of light collected onto a disc so as to form a bit onto a recording layer thereon is restricted by diffraction limit, there is limit to improve a recording density.
Trends toward large storage in recording medium needs a new optical recording /reproducing method capable of overcoming the limit of the conventional optical recording/reproducing method. Recently, researches on near field recording/reproducing using a near field capable of improving a recording capacity epochally have increased.
Principals of the near field optical recording/reproducing will be described as follows. In light incident to a lens at an angle not less than a critical angle of the lens, when the light proceeds from an optically dense portion to an optically rare portion in a refractive index, the light is total-reflected. Herein, by the total reflection of the light, light having very low brightness exists on the surface of the lens, it is called an evanescent wave. By using the evanescent wave, it is possible to have high resolving power that could not have in the conventional far field due to absolute limit, namely, diffraction limit occurred by a light diffraction phenomenon.
A near field optical recording/reproducing instrument generates an evanescent wave on the surface of a lens by total-reflecting light in the lens, and accordingly data can be recorded and reproduced by coupling the evanescent wave to a disc.
FIGS. 1 and 2 respectively illustrate a structure of the conventional near field optical recording/reproducing apparatus. Herein, FIG. 1 is a plan view, and FIG. 2 is an enlarged-sectional view of a slider having SIL.
As depicted in FIG. 1, the conventional near field optical recording/reproducing apparatus includes a swing arm 21 installed so as to perform a reciprocating rotation; an actuator 23 for rotationally driving the swing arm 21; and a head 30 installed at the end of the swing arm 21 in order to scan a track of a disc 10 by being lifted above the disc 10 by air dynamic pressure.
As depicted in FIG. 2, the head 30 includes an objective lens 31, an opposed lens 32 separated from the objective lens 31 by a focus distance of the objective lens 31 and a slider 33 for fixing the lenses 31, 32. Herein, it is general to use a solid immersion lens (SIL) as the opposed lens, namely converging lens 32.
In addition, in order to lift the slider 33 above the disc 10, an air bearing system (ABS) 36 for generating air pressure between the disc 10 and the slider 33 is installed at the bottom surface of the slider 33.
In the near field optical recording/reproducing apparatus, while the head 30 in a lifted state by the ABS 36 moves above the rotational disc 10, data is recorded/reproduced onto the disc 10.
In the meantime, when the head 30 in a lifted state by the ABS 36 moves above the rotational disc 10, because of the ABS 36 installed at the both sides of the opposed lens 32, the bottom surface of the slider 33 has not to escape from the inner or outer circumference of a recording capable region of the disc 10, and accordingly there are regions incapable of recording/reproducing on the inner or outer circumference of the disc 10.
In particular, according to miniaturization of a portable terminal, etc. using a recording/reproducing apparatus, it is required for a disc as a recording medium to have a small size and a high capacity, and accordingly existence of regions incapable of recording/reproducing is big restriction in increasing of a recording capacity of a disc.
In order to solve the above-mentioned problem, it is an object of the present invention to provide a head of an optical recording/reproducing apparatus which is capable of increasing recordable region on the inner or outer circumference of a disc.
In order to achieve the above-mentioned object, a head of an optical recording/reproducing apparatus in accordance with the present invention includes a slider at which an objective lens is installed at a top surface of the slider and a solid immersion lens (SIL) installation hole formed below the objective lens penetrates toward a bottom surface of the slider in order to install a SIL; a flying means fixedly installed around the SIL installation hole at the bottom surface of the slider in order to lift the slider above an optical recording medium; wherein a sectional area of the slider parallel to a surface of the optical recording medium increases from the bottom surface to the top surface of the slider.
In addition, an optical recording/reproducing apparatus in accordance with the present invention includes a slider at which an objective lens is installed at a top surface of the slider and a solid immersion lens (SIL) installation hole formed below the objective lens penetrates toward to the bottom surface of the slider in order to install a SIL; a flying means fixedly installed around the SIL installation hole at the bottom surface of the slider in order to lift the slider above an optical recording medium; wherein a sectional area of the slider parallel to a surface of the optical recording medium increases from the bottom surface to the top surface.